Base de dados : MEDLINE
Pesquisa : B03.660.075.655.070 [Categoria DeCS]
Referências encontradas : 166 [refinar]
Mostrando: 1 .. 10   no formato [Longo]

página 1 de 17 ir para página                         

  1 / 166 MEDLINE  
              next record last record
seleciona
para imprimir
Fotocópia
Texto completo
PMID:28389432
Autor:Yeates JAM; Nghe P; Lehman N
Endereço:Department of Chemistry, Portland State University, Portland, Oregon 97207, USA.
Título:Topological and thermodynamic factors that influence the evolution of small networks of catalytic RNA species.
Fonte:RNA; 23(7):1088-1096, 2017 Jul.
ISSN:1469-9001
País de publicação:United States
Idioma:eng
Resumo:An RNA-directed recombination reaction can result in a network of interacting RNA species. It is now becoming increasingly apparent that such networks could have been an important feature of the RNA world during the nascent evolution of life on the Earth. However, the means by which such small RNA networks assimilate other available genotypes in the environment to grow and evolve into the more complex networks that are thought to have existed in the prebiotic milieu are not known. Here, we used the ability of fragments of the group I intron ribozyme to covalently self-assemble via genotype-selfish and genotype-cooperative interactions into full-length ribozymes to investigate the dynamics of small (three- and four-membered) networks. We focused on the influence of a three-membered core network on the incorporation of additional nodes, and on the degree and direction of connectivity as single new nodes are added to this core. We confirmed experimentally the predictions that additional links to a core should enhance overall network growth rates, but that the directionality of the link (a "giver" or a "receiver") impacts the growth of the core itself. Additionally, we used a simple mathematical model based on the first-order effects of lower-level interactions to predict the growth of more complex networks, and find that such a model can, to a first approximation, predict the ordinal rankings of nodes once a steady-state distribution has been reached.
Tipo de publicação: JOURNAL ARTICLE
Nome de substância:0 (GIR1 ribozyme); 0 (RNA, Bacterial); 0 (RNA, Catalytic)


  2 / 166 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
PMID:28258136
Autor:Pacheco-Sánchez D; Molina-Fuentes Á; Marín P; Medina-Bellver JI; González-López Ó; Marqués S
Endereço:Consejo Superior de Investigaciones Científicas, Estación Experimental del Zaidín, Department of Environmental Protection, Granada, Spain.
Título:The Azoarcus anaerobius 1,3-Dihydroxybenzene (Resorcinol) Anaerobic Degradation Pathway Is Controlled by the Coordinated Activity of Two Enhancer-Binding Proteins.
Fonte:Appl Environ Microbiol; 83(9), 2017 May 01.
ISSN:1098-5336
País de publicação:United States
Idioma:eng
Resumo:The anaerobic resorcinol degradation pathway in is unique in that it uses an oxidative rather than a reductive strategy to overcome the aromatic ring stability in degradation of this compound, in a process that is dependent on nitrate respiration. We show that the pathway is organized in five transcriptional units, three of which are inducible by the presence of the substrate. Three σ -dependent promoters located upstream from the three operons coding for the main pathway enzymes were identified, which shared a similar structure with conserved upstream activating sequences (UASs) located at 103 to 111 bp from the transcription start site. Expression of the pathway is controlled by the bacterial enhancer-binding proteins (bEBPs) RedR1 and RedR2, two homologous regulators that, despite their high sequence identity (97%), have nonredundant functions: RedR2, the master regulator which also controls RedR1 expression, is itself able to promote transcription from two of the promoters, while RedR1 activity is strictly dependent on the presence of RedR2. The two regulators were shown to interact with each other, suggesting that the natural mode of activation is by forming heterodimers, which become active in the presence of the substrate after its metabolization to hydroxybenzoquinone through the pathway enzymes. The model structure of the N-terminal domain of the proteins is composed of tandem GAF and PAS motifs; the possible mechanisms controlling the activity of the regulators are discussed. is a strict anaerobe that is able to use 1,3-dihydroxybenzene as the sole carbon source in a process that is dependent on nitrate respiration. We have shown that expression of the pathway is controlled by two regulators of almost identical sequences: the bEBPs RedR1 and RedR2, which share 97% identity. These regulators control three promoters with similar structure. Despite their sequence identity, the two bEBPs are not redundant and are both required for maximum pathway expression. In fact, the two proteins function as heterodimers and require activation by the pathway intermediate hydroxyhydroquinone. The structure of the domain sensing the activation signal resembles that of regulators that are known to interact with other proteins.
Tipo de publicação: JOURNAL ARTICLE
Nome de substância:0 (DNA-Binding Proteins); 0 (Resorcinols); YUL4LO94HK (resorcinol)


  3 / 166 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
PMID:27727497
Autor:Sarkar A; Marszalkowska M; Schäfer M; Pees T; Klingenberg H; Macht F; Reinhold-Hurek B
Endereço:Faculty of Biology and Chemistry, Department of Microbe-Plant Interactions, University of Bremen, P.O. Box 33 04 40, Bremen, 28334, Germany.
Título:Global expression analysis of the response to microaerobiosis reveals an important cue for endophytic establishment of Azoarcus sp. BH72.
Fonte:Environ Microbiol; 19(1):198-217, 2017 Jan.
ISSN:1462-2920
País de publicação:England
Idioma:eng
Resumo:The endophyte Azoarcus sp. BH72, fixing nitrogen microaerobically, encounters low O tensions in flooded roots. Therefore, its transcriptome upon shift to microaerobiosis was analyzed using oligonucleotide microarrays. A total of 8.7% of the protein-coding genes were significantly modulated. Aerobic conditions induced expression of genes involved in oxidative stress protection, while under microaerobiosis, 233 genes were upregulated, encoding hypothetical proteins, transcriptional regulators, and proteins involved in energy metabolism, among them a cbb -type terminal oxidase contributing to but not essential for N fixation. A newly established sensitive transcriptional reporter system using tdTomato allowed to visualize even relatively low bacterial gene expression in association with roots. Beyond metabolic changes, low oxygen concentrations seemed to prime transcription for plant colonization: Several genes known to be required for endophytic rice interaction were induced, and novel bacterial colonization factors were identified, such as azo1653. The cargo of the type V autotransporter Azo1653 had similarities to the attachment factor pertactin. Although for short term swarming-dependent colonization, it conferred a competitive disadvantage, it contributed to endophytic long-term establishment inside roots. Proteins sharing such opposing roles in the colonization process appear to occur more generally, as we demonstrated a very similar phenotype for another attachment protein, Azo1684. This suggests distinct cellular strategies for endophyte establishment.
Tipo de publicação: JOURNAL ARTICLE
Nome de substância:0 (Bacterial Proteins)


  4 / 166 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
PubMed Central Texto completo
Texto completo
PMID:27501145
Autor:van Schie SN; Sengupta RN; Herschlag D
Endereço:Department of Biochemistry, Stanford University, Stanford, California, 94305, United States of America.
Título:Differential Assembly of Catalytic Interactions within the Conserved Active Sites of Two Ribozymes.
Fonte:PLoS One; 11(8):e0160457, 2016.
ISSN:1932-6203
País de publicação:United States
Idioma:eng
Resumo:Molecular recognition is central to biology and a critical aspect of RNA function. Yet structured RNAs typically lack the preorganization needed for strong binding and precise positioning. A striking example is the group I ribozyme from Tetrahymena, which binds its guanosine substrate (G) orders of magnitude slower than diffusion. Binding of G is also thermodynamically coupled to binding of the oligonucleotide substrate (S) and further work has shown that the transition from E•G to E•S•G accompanies a conformational change that allows G to make the active site interactions required for catalysis. The group I ribozyme from Azoarcus has a similarly slow association rate but lacks the coupled binding observed for the Tetrahymena ribozyme. Here we test, using G analogs and metal ion rescue experiments, whether this absence of coupling arises from a higher degree of preorganization within the Azoarcus active site. Our results suggest that the Azoarcus ribozyme forms cognate catalytic metal ion interactions with G in the E•G complex, interactions that are absent in the Tetrahymena E•G complex. Thus, RNAs that share highly similar active site architectures and catalyze the same reactions can differ in the assembly of transition state interactions. More generally, an ability to readily access distinct local conformational states may have facilitated the evolutionary exploration needed to attain RNA machines that carry out complex, multi-step processes.
Tipo de publicação: JOURNAL ARTICLE
Nome de substância:0 (GIR1 ribozyme); 0 (Metals); 0 (Oligonucleotides); 0 (RNA, Catalytic); 12133JR80S (Guanosine)


  5 / 166 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
PMID:27450529
Autor:Zamarro MT; Martín-Moldes Z; Díaz E
Endereço:Environmental Biology Department, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, Madrid, 28040, Spain.
Título:The ICE of Azoarcus sp. CIB, an integrative and conjugative element with aerobic and anaerobic catabolic properties.
Fonte:Environ Microbiol; 18(12):5018-5031, 2016 Dec.
ISSN:1462-2920
País de publicação:England
Idioma:eng
Resumo:Integrative and conjugative elements (ICE) play a major role in aerobic degradation of aromatic compounds, but they have not yet been shown to be involved in anaerobic degradation. We have characterized here the ICE element which endows to the beta-proteobacterium Azoarcus sp. CIB with the ability to utilize aromatic hydrocarbons. The core region of ICE , which shows a remarkable synteny with that of ICEclc-like elements, allows its own intracellular and intercellular mobility. ICE integrates at the tRNAGly of the host chromosome, but it can also excise to produce a ready to transfer circular form. The adaptation modules of ICE represent a unique combination of gene clusters for aerobic (tod genes) and anaerobic (bss-bbs and mbd genes) degradation of certain aromatic hydrocarbons, e.g., toluene, m-xylene and cumene. Transfer of ICE to other Azoarcus strains, e.g., A. evansii, confers them the ability to degrade aromatic hydrocarbons both aerobically and anaerobically. Interestingly, ICE allows Cupriavidus pinatubonensis, a bacterium unable to degrade anaerobically aromatic compounds, to grow with m-xylene under anoxic conditions. Thus, ICE constitutes the first mobile genetic element able to expand the catabolic abilities of certain bacteria for the removal of aromatic hydrocarbons either in the presence or absence of oxygen.
Tipo de publicação: JOURNAL ARTICLE
Nome de substância:0 (Bacterial Proteins); 0 (DNA Transposable Elements); 0 (Hydrocarbons, Aromatic); 0 (Xylenes); 3FPU23BG52 (Toluene); O9XS864HTE (3-xylene)


  6 / 166 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
PMID:27387486
Autor:Junghare M; Spiteller D; Schink B
Endereço:Konstanz Research School of Chemical Biology, University of Konstanz, Konstanz, D-78457, Germany. madan.junghare@uni-konstanz.de.
Título:Enzymes involved in the anaerobic degradation of ortho-phthalate by the nitrate-reducing bacterium Azoarcus sp. strain PA01.
Fonte:Environ Microbiol; 18(9):3175-88, 2016 Sep.
ISSN:1462-2920
País de publicação:England
Idioma:eng
Resumo:The pathway of anaerobic degradation of o-phthalate was studied in the nitrate-reducing bacterium Azoarcus sp. strain PA01. Differential two-dimensional protein gel profiling allowed the identification of specifically induced proteins in o-phthalate-grown compared to benzoate-grown cells. The genes encoding o-phthalate-induced proteins were found in a 9.9 kb gene cluster in the genome of Azoarcus sp. strain PA01. The o-phthalate-induced gene cluster codes for proteins homologous to a dicarboxylic acid transporter, putative CoA-transferases and a UbiD-like decarboxylase that were assigned to be specifically involved in the initial steps of anaerobic o-phthalate degradation. We propose that o-phthalate is first activated to o-phthalyl-CoA by a putative succinyl-CoA-dependent succinyl-CoA:o-phthalate CoA-transferase, and o-phthalyl-CoA is subsequently decarboxylated to benzoyl-CoA by a putative o-phthalyl-CoA decarboxylase. Results from in vitro enzyme assays with cell-free extracts of o-phthalate-grown cells demonstrated the formation of o-phthalyl-CoA from o-phthalate and succinyl-CoA as CoA donor, and its subsequent decarboxylation to benzoyl-CoA. The putative succinyl-CoA:o-phthalate CoA-transferase showed high substrate specificity for o-phthalate and did not accept isophthalate, terephthalate or 3-fluoro-o-phthalate whereas the putative o-phthalyl-CoA decarboxylase converted fluoro-o-phthalyl-CoA to fluoro-benzoyl-CoA. No decarboxylase activity was observed with isophthalyl-CoA or terephthalyl-CoA. Both enzyme activities were oxygen-insensitive and inducible only after growth with o-phthalate. Further degradation of benzoyl-CoA proceeds analogous to the well-established anaerobic benzoyl-CoA degradation pathway of nitrate-reducing bacteria.
Tipo de publicação: JOURNAL ARTICLE
Nome de substância:0 (Acyl Coenzyme A); 0 (Bacterial Proteins); 0 (Benzoates); 0 (Nitrates); 0 (Phthalic Acids); 121-91-5 (isophthalate); 604-98-8 (succinyl-coenzyme A); 6756-74-7 (benzoyl-coenzyme A); 6O7F7IX66E (phthalic acid)


  7 / 166 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
PMID:27378777
Autor:Kilburn D; Behrouzi R; Lee HT; Sarkar K; Briber RM; Woodson SA
Endereço:T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA.
Título:Entropic stabilization of folded RNA in crowded solutions measured by SAXS.
Fonte:Nucleic Acids Res; 44(19):9452-9461, 2016 Nov 02.
ISSN:1362-4962
País de publicação:England
Idioma:eng
Resumo:Non-coding RNAs must fold into specific structures that are stabilized by metal ions and other co-solutes in the cell's interior. Large crowder molecules such as PEG stabilize a bacterial group I ribozyme so that the RNA folds in low Mg concentrations typical of the cell's interior. To understand the thermodynamic origins of stabilization by crowder molecules, small angle X-ray scattering was used to measure the folding and helix assembly of a bacterial group I ribozyme at different temperatures and in different MgCl and polyethylene glycol (PEG) concentrations. The resulting phase diagrams show that perturbations to folding by each variable do not overlap. A favorable enthalpy change drives the formation of compact, native-like structures, but requires Mg ions at all temperatures studied (5-55°C). PEG reduces the entropic cost of helix assembly and increases correlations between RNA segments at all temperatures. The phase diagrams also revealed a semi-compact intermediate between the unfolded and folded ensemble that is locally more flexible than the unfolded state, as judged by SHAPE modification. These results suggest that environmental variables such as temperature and solute density will favor different types of RNA structures.
Tipo de publicação: JOURNAL ARTICLE
Nome de substância:0 (Nucleotides); 0 (RNA, Bacterial); 0 (Solutions); 02F3473H9O (Magnesium Chloride); 30IQX730WE (Polyethylene Glycols); 63231-63-0 (RNA)


  8 / 166 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
PubMed Central Texto completo
Texto completo
PMID:27301452
Autor:Fernández-Llamosas H; Castro L; Blázquez ML; Díaz E; Carmona M
Endereço:Environmental Biology Department, Centro de Investigaciones Biológicas-CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain.
Título:Biosynthesis of selenium nanoparticles by Azoarcus sp. CIB.
Fonte:Microb Cell Fact; 15(1):109, 2016 Jun 14.
ISSN:1475-2859
País de publicação:England
Idioma:eng
Resumo:BACKGROUND: Different bacteria have been reported so far that link selenite resistance to the production of metallic selenium nanoparticles (SeNPs). Although SeNPs have many biotechnological applications in diverse areas, the molecular mechanisms involved in their microbial genesis are not fully understood. The Azoarcus genus is a physiologically versatile group of beta-proteobacteria of great environmental relevance. Azoarcus sp. CIB is a facultative anaerobe that combines the ability to degrade under aerobic and/or anaerobic conditions a wide range of aromatic compounds, including some toxic hydrocarbons such as toluene and m-xylene, with an endophytic life style in the root of rice. We unravel here an additional physiological feature of the strain CIB that is related to its resistance to selenium oxyanions and the formation of SeNPs. RESULTS: This work is the first report of a member of the Azoarcus genus that is able to anaerobically grow in the presence of selenite. Electron microscopy preparations and X-ray spectroscopy analyses demonstrate the reduction of selenite to spherical electron-dense SeNPs whose average size was 123 ± 35 nm of diameter. Our data suggest that the main molecular mechanism of selenite resistance resides on an energy-dependent selenite exporter. Azoarcus cells trigger the synthesis of SeNPs when they reach the stationary-phase of growth, and either the exhaustion of electron donor or acceptor, both of which lead to starvation conditions, produce the reduction of selenite to red elemental selenium. Azoarcus becomes a promising biocatalyst, either as whole cells or cellular extracts, for the anaerobic and/or aerobic green synthesis of SeNPs. CONCLUSIONS: Azoarcus turns out to be a new eco-friendly system to reduce selenite and produce spherical SeNPs. Moreover, this is the first report of a rice endophyte able to produce SeNPs. Since Azoarcus is also able to degrade both aerobically and anaerobically toxic aromatic compounds of great environmental concern, it becomes a suitable candidate for a more sustainable agricultural practice and for bioremediation strategies.
Tipo de publicação: JOURNAL ARTICLE
Nome de substância:F6A27P4Q4R (Selenious Acid); H6241UJ22B (Selenium)


  9 / 166 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
PMID:26825521
Autor:Benedek T; Táncsics A; Szabó I; Farkas M; Szoboszlay S; Fábián K; Maróti G; Kriszt B
Endereço:Regional University Center of Excellence in Environmental Industry, Szent István University, Páter K. u. 1, Gödöllo, 2100, Hungary.
Título:Polyphasic analysis of an Azoarcus-Leptothrix-dominated bacterial biofilm developed on stainless steel surface in a gasoline-contaminated hypoxic groundwater.
Fonte:Environ Sci Pollut Res Int; 23(9):9019-35, 2016 May.
ISSN:1614-7499
País de publicação:Germany
Idioma:eng
Resumo:Pump and treat systems are widely used for hydrocarbon-contaminated groundwater remediation. Although biofouling (formation of clogging biofilms on pump surfaces) is a common problem in these systems, scarce information is available regarding the phylogenetic and functional complexity of such biofilms. Extensive information about the taxa and species as well as metabolic potential of a bacterial biofilm developed on the stainless steel surface of a pump submerged in a gasoline-contaminated hypoxic groundwater is presented. Results shed light on a complex network of interconnected hydrocarbon-degrading chemoorganotrophic and chemolitotrophic bacteria. It was found that besides the well-known hydrocarbon-degrading aerobic/facultative anaerobic biofilm-forming organisms (e.g., Azoarcus, Leptothrix, Acidovorax, Thauera, Pseudomonas, etc.), representatives of Fe(2+)-and Mn(2+)-oxidizing (Thiobacillus, Sideroxydans, Gallionella, Rhodopseudomonas, etc.) as well as of Fe(3+)- and Mn(4+)-respiring (Rhodoferax, Geobacter, Magnetospirillum, Sulfurimonas, etc.) bacteria were present in the biofilm. The predominance of ß-Proteobacteria within the biofilm bacterial community in phylogenetic and functional point of view was revealed. Investigation of meta-cleavage dioxygenase and benzylsuccinate synthase (bssA) genes indicated that within the biofilm, Azoarcus, Leptothrix, Zoogloea, and Thauera species are most probably involved in intrinsic biodegradation of aromatic hydrocarbons. Polyphasic analysis of the biofilm shed light on the fact that subsurface microbial accretions might be reservoirs of novel putatively hydrocarbon-degrading bacterial species. Moreover, clogging biofilms besides their detrimental effects might supplement the efficiency of pump and treat systems.
Tipo de publicação: JOURNAL ARTICLE
Nome de substância:0 (Gasoline); 0 (Hydrocarbons); 0 (Hydrocarbons, Aromatic); 0 (Water Pollutants, Chemical); 12597-68-1 (Stainless Steel); EC 4.1.- (Carbon-Carbon Lyases); EC 4.1.99.- (benzylsuccinate synthase)


  10 / 166 MEDLINE  
              first record previous record
seleciona
para imprimir
Fotocópia
Texto completo
PMID:26497112
Autor:Huang C; Li ZL; Chen F; Liu Q; Zhao YK; Gao LF; Chen C; Zhou JZ; Wang AJ
Endereço:State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, PR China.
Título:Efficient regulation of elemental sulfur recovery through optimizing working height of upflow anaerobic sludge blanket reactor during denitrifying sulfide removal process.
Fonte:Bioresour Technol; 200:1019-23, 2016 Jan.
ISSN:1873-2976
País de publicação:England
Idioma:eng
Resumo:In this study, two lab-scale UASB reactors were established to testify S(0) recovery efficiency, and one of which (M-UASB) was improved from the previous T-UASB by shortening reactor height once S(2-) over oxidation was observed. After the height was shortened from 60 to 30cm, S(0) recovery rate was improved from 7.4% to 78.8%, and while, complete removal of acetate, nitrate and S(2-) was simultaneously maintained. Meanwhile, bacterial community distribution was homogenous throughout the reactor, with denitrifying sulfide oxidization bacteria predominant, such as Thauera and Azoarcus spp., indicating the optimized condition for S(0) recovery. The effective control of working height/volume in reactors plays important roles for the efficient regulation of S(0) recovery during DSR process.
Tipo de publicação: JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
Nome de substância:0 (Acetates); 0 (Nitrates); 0 (Sewage); 0 (Sulfates); 0 (Sulfides); 70FD1KFU70 (Sulfur); 7440-44-0 (Carbon)



página 1 de 17 ir para página                         
   


Refinar a pesquisa
  Base de dados : MEDLINE Formulário avançado   

    Pesquisar no campo  
1  
2
3
 
           



Search engine: iAH v2.6 powered by WWWISIS

BIREME/OPAS/OMS - Centro Latino-Americano e do Caribe de Informação em Ciências da Saúde